CallRail, CloudTalk.io, Sideline, Grasshopper Virtual Phone, JustCall, MightyCall, RingRoost, HulloMail, Vumber, Call Me Private, Telzio, Callcap, Mitel, Cloud Telephony, Natterbox, Uno.im, Talkdesk, Tackle, Anello Voice, Text Me Private, UniTel Voice, Truly Wireless, Ringio are some alternatives to Slingshot VoIP.